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The Denka Performance Elastome plant on River Road in Laplace, La. Wednesday, Dec. 11, 2019.

An LSU audit aimed at measuring how completely Louisiana's cancer incidence database has counted new cancer cases around a controversial manufacturer in St. John the Baptist Parish concludes that the Louisiana Tumor Registry appears to have found all "reportable" cases between 2009 and 2018.

But the new LSU School of Public Health report, released Monday, is unlikely to settle the debate over whether the Denka Performance Elastomers plant in Reserve poses a grave cancer risk. In fact, the report takes pains to say it draws no conclusions about whether the Denka plant, and the chloroprene it emits, are a cause of any of the cancers recorded in the tumor registry — or any other health effects.

"This report in no way implies that there are no health effects from long-term exposure to chloroprene," the report says.

The chemical is used in the manufacture of neoprene, a rubbery material used in a variety of commercial and household products. Since 2010, chloroprene been designated a "likely carcinogen" by the U.S. Environmental Protection Agency.

LSU health researchers conducted a survey of homes around the Denka complex to answer community concerns that the tumor registry was underestimating nearby cancer incidences. 

Those concerns have been around for years. In the new report, LSU officials said they were heightened after the University Network for Human Rights, an advocacy group, surveyed more than 500 homes in the neighborhood and found that there were significantly elevated cancer prevalence rates within about 1.5 miles of the plant. The group's 2019 report, which came in for criticism over its methods but has since been published in a peer-reviewed journal, found even higher prevalence rates within under a mile of the Mississippi River facility.

Dr. Edward Trapido, professor and associate dean for research at LSU Health New Orleans School of Public Health, said that the Tumor Registry "is not the right entity to answer" the questions raised by residents concerned about Denka' emissions.

“The LTR is an exceptional resource for learning about types of cancer, their frequency, the rates at which they occur, the distribution of cases, information on cancer stage and pathology, cancer treatment, and cancer survival, but it does not contain information on what may have caused the cancers," he said in a statement. "The registry does not collect data on possible contributing factors or environmental conditions to which persons with cancer may have been exposed. That is the purview of other entities and scientists."

The new LSU study does not detail how the cancer cases it found were spread out geographically.

That's a key deficiency, according to Kimberly Terrell, director of community outreach for Tulane Environmental Law Clinic, whom LSU asked for input on the final report. She said the analysis doesn't answer what is the overriding concern in the community -- what effect chloroprene is having on people and how can those effects be eliminated.

"They answered a question that I'm not sure anybody was asking," Terrell said.

In 2015, five years after designating chloroprene a likely carcinogen, the EPA concluded that the cancer risk from airborne pollutants in census tracts nearest the Denka plant was the highest in the nation.

That finding, which industry groups have challenged and state regulators have downplayed, prompted lawsuits from residents claiming health effects from years of emissions from the complex, which opened in 1969. Some of those claims have failed in court, but others remain pending.

Jim Harris, spokesman for Denka, said Monday that the new LSU study verifies the accuracy of registry data that has shown for years that there is nothing unusual about St. John the Baptist Parish's cancer rates.

"(The cancer registry's) data is consistent with numerous epidemiological studies, including a major one recently updated by researchers at the University of Pittsburgh, that show there is no increase in cancer incidence" near the Denka plant, he said.

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Harris was pointing to a recently published long-term follow-up study of workers in two U.S. chloroprene plants, including the one in Reserve, that found those workers' risk of death from lung or liver cancer is unrelated to exposure to chloroprene or vinyl chloride. 

Harris said that additional scientific study has shown the cancer risk level that EPA has attributed to chloroprene could be vastly overstated.

Terrell saw some significance in Trapido's and the LSU analysis's statement Monday that the registry's data does not examine the causes of cancer cases.

The registry focuses on cancer incidence, which can be caused by a number of factors, instead of the risk faced by people exposed to emissions from industrial operations. In Terrell's view, that has allowed companies and by the state Department of Environmental Quality to misconstrue its significance. 

To figure out whether the tumor registry was recording all cancer cases, LSU determined that researchers would need to interview enough households to find at least 47 reportable cancer incidences, or 10% of the cancer cases that could be expected in the area.

Under the survey design, LSU researchers interviewed one individual in the household, who reported on the health status of all those in the home. Respondents had to be at least 21 and knowledgeable about the family's health.

The surveys were conducted door-to-door until the coronavirus forced researchers in March 2020 to start filling out surveys by telephone. In the end, LSU collected responses from 179 households, or about 10% of all homes, between January 2020 to January 2021.

Researchers then checked the 141 reported cancer cases from that group against the tumor registry, medical records and other information to verify accuracy. 

Researchers found 50 "reportable cancers" between 2009 and 2018 and found that all of them had already been collected by the Louisiana Tumor Registry.

Another 91 cancer incidences were reported by the households interviewed, but researchers excluded them for a variety of reasons. The largest share, 36, were reportable cancer cases that were listed in the tumor registry, but recorded before the 10-year time period being examined.

Others excluded ended up being people who had no cancer diagnosis once medical records were examined. And some cases involved people who lived out of state at the time of diagnosis.

Ten excluded cases were what are called "non-reportable cancers," which include some skin cancers and others that the LSU report says don't fit national standards for cancer reporting. 

The EPA began measuring how much chloroprene was being released into the air surrounding Denka in 2016. That work showed spikes hundreds of times over the agency's recommended exposure threshold of no more than 0.2 micrograms per cubic meter of air.

In 2020, the EPA confirmed Denka had cut its emissions by 85% after installing $35 million in new control equipment, but critics say that still isn't low enough to reach the EPA's recommended threshold.

The neoprene facility is now the only complex of its kind in the nation.


Email David J. Mitchell at dmitchell@theadvocate.com

Follow David J. Mitchell on Twitter, @NewsieDave.